1. Field of the Invention
This invention relates to multiple glazed window units and also relates to sealing and spacing means for such units. In another aspect, the invention further relates to the use of a specific cold flowable, mastic, sealant composition in combination with an elongated, flexible, dehydrator strip adhesively secured to foil strip member.
2. Brief Description of the Prior Art
U.S. Pat. Nos. 3,657,900 and 3,699,785, both to Bowser et al., disclose sealing and spacing means for multiple glazed windows. The sealing and spacing means consists of flexible carrier strips such as aluminum foil, and adhered to one side of the carrier strip is an elongated ribbon of sealant material and an elongated resilient spacer-dehydrator element secured to the carrier strip through the sealant. The carrier strip is slightly wider than the ribbon of sealant and the sealant wider than the spacer-dehydrator element. Each of the three elements are coextensive in length and symmetrically disposed on either side of a centerline through the length of the composite element. Examples of suitable sealant compositions are butyl rubber-based sealants, such as are disclosed in U.S. Pat. No. 2,974,377 to Kunkle.
U.S. Pat. Nos. 3,758,996 and 3,791,910both to Bowser, disclose similar sealing and spacing means for multiple glazed windows and also disclose that the sealant composition can be a hot melt adhesive. Also, U.S. Pat. No. 3,791,910 discloses that the sealant composition can be a cold flowable, butyl rubber-based sealant composition.
Although the above-mentioned sealing and spacing means provide definite advantages in fabricating multiple glazed windows, there are certain shortcomings associated with these sealing and spacing means. As mentioned in both the U.S. Pat. Nos. 3,657,900 and 3,699,785, the butyl sealants, although providing air-tight, durable seals, are not particularly good adhesives. When the composite element is coiled for packaging and shipping with the spacer-dehydrator element nearest the core of the coil, the spacer-dehydrator element moves relative to the sealant causing the spacer-dehydrator to assume a wavy or undulatory appearance. The butyl sealant does not have sufficient adhesive properties to hold the spacer-dehydrator element to the carrier tape in a straight line alignment. When the sealing and spacing unit is removed from the package and unrolled, the wavy spacer-dehydrator can only be straightened with difficulty. Also, when the sealing and spacing unit of the prior art is applied to spaced-apart glass sheets and bent around 90.degree. corners at the ends of the sheets, the mastic will not adequately secure a spacer-dehydrator to the carrier tape and the spacer-dehydrator will "bunch together" putting stress on the corners of the multiple glazed window and at times permitting the bunched spacer-dehydrator to extend into the viewing area. To avoid this problem, a notch of the spacer-dehydrator element must be removed from the corner areas of the composite element.
The above problems can be overcome if the sealant composition is one which has strong adhesive and cohesive properties, thereby firmly securing the spacer-dehydrator element to the carrier strip and preventing it from undulating when a composite strip is coiled for packaging or bent around 90.degree. corners in multiple glazed windows. In the aforementioned patents, U.S. Pat. Nos. 3,758,996 and 3,791,910, a hot melt adhesive is recommended for the sealant compositions. Hot melt adhesives have very strong adhesive and cohesive properties making them attractive candidates for securing the spacer-dehydrator to the carrier strip. Unfortunately, hot melt adhesives have a number of shortcomings associated with them for use in sealing multiple glazed window units. First of all, the hot melt adhesives are not nearly as good sealants as are the butyl rubber-based materials. They are more rigid and are not nearly as durable as butyl rubber-based materials and hot melt adhesives are pervious to moisture vapor. In addition, hot melt adhesives are not cold flowable and are only flowable when heated.
With hot melt adhesives, the composite sealing and spacing element or the glass must be heated so as to cause the hot melt adhesive to flow into hermetically sealing contact with the edges of the glass sheets. Heating either the composite element or the glass presents a definite assembling disadvantage. Further, heating may cause deformation of the flexible spacer-dehydrator element and also may cause unwanted condensation in the interior of the multiple glazed unit upon cooling of the heated member. With the butyl sealants, on the other hand, mere pressure at room temperature is sufficient to cause the sealant to flow into hermetically sealing contact with the edges of the glass sheets. With the cold flowable butyl sealants of U.S. Pat. No. 3,791,910, very light pressure such as from a hand roller is all that is necessary.
From the above consideration of the prior art, it appears that there is a need for an improved sealing and spacing unit for multiple glazed windows.
It is an object of the present invention to provide such a sealing and spacing unit. More specifically, it is an object of the present invention to provide a sealing and spacing unit which comprises an elongated, flexible, moisture-impervious base or ribbon, a sealant and a spacer-dehydrator element which can be applied to the peripheral edges of spaced-apart glass sheets and which will hermetically seal the edges of the glass sheets by merely pressing the unit to the edges of the glass sheets so as to flow the sealant into hermetically sealing contact with the edges of the glass sheets; further, the unit is one in which the spacer-dehydrator element is firmly adhered to the ribbon so that it is maintained in a straight alignment and does not take on a wavy or undulating appearance when the composite unit is coiled for packaging or bent around 90.degree. corners in multiple glazed window units.
It is a further object of the present invention to provide multiple glazed windows employing such a sealing and spacing unit.
It is yet a further object of the present invention to employ a novel, cold flowable, mastic sealant in combination with a carrier strip and a spacer-dehydrator element to form a preferred spacing and sealing unit.